Electric heater



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STATES n .11,531,308 PATENT lorries.

` NsoN s. aren mal Louis J. mmm, or Bnooxmm, NEW Yonx, AssreNons To DU- ranqu'm, mro'rxa normusn conm, .a conromrron 015m Yonx.

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application mea rebmry 1, 1m.' serial no. 618,368.

To `all 'whom it may concern:

Beitknown that we, ANsoN S. RIGE and Louis J. FULLER, both citizens of the United States, residing -in Brooklyn, county of Kings, wState, of New York, and whose postotlice address'isl Duparquet, Huot & Moneuse Company, 10S-114 West 22nd Street, New York,-New York, have invented certain new and useful Improvements in Electric Heaters; and we d o hereby declare the fol# lowing to be a full, clear, and exact description ofthe invention, such as will enable others Yskilled in vthe art to which it appertains to` make `and use the same.

This invention relates to electric heaters in which a surface' is conductively Aheated by adjacent resistance elements, and hasfor its object the provision of an improvedstructure whereby the .Surface is more uniformlyY c and effectively heated `and whereby the construction of the heater is simplified.

This application is a continuation in part our copending application, Serial No.

482,881, filed July 7,1921.

It is well known to construct heaters retainingheatng elements in grooves formed in the metallic surface to be heated, called the surface plate, and this construction has been extensively used. Theusual method hasv been to embed the heater element in plastic cement, taking care that the' element does not make contact with the plate vat any point. This method, however, gives rise to many defective heaters, as it is extremely diicult to maintain an even layer of cement between the elementand the surface plate. Even though anA electrical-short circuit does not result, there is usually uneven heating of the plate surface because of the varying disbetwecn the'heater coils and the Vplatte. to behe'ated, thepplate being` hottest whereff `the thermal pathis shortest. Further, a great amount of heat is dissipated in the insulating cement with attendant loss in the -amount of heat that reaches the surface plate and reduction Vinthe eciency of the heater.

Thel construction provided by the present invention eliminates these difliculties and ref sults in a greatly improvedheater, In accordance with this invention, the surface plate is provided with ribs which 'stand out from the surface preferably-a distance greater than the heating element which is to be used. The heating eleinent may be retained in the grooves between these ribs, the ribs Serving to conduct the heat from the coils to the plate. In order that the element may be positively positioned, insulator channels, preferably of lava, are first laid in the grooves between the ribs. and the elementn's then placed in the insulator channels. By vthis means the element may be evenly spaced from the metallic plate and its integral ribs and the possibility of contact between the element and the plate is eliminated. Because the Vwalls of the channels lare of uniform thickness, the thermal path to the surface plate is substantially constant in all directions and the plate is accordingly uniformly heated.

Further advantages will appear fromr the accompanying drawings and following description, which disclose more in detail a V preferred embodiment. In the drawings:

Fig. 1 is a vertical section 'through a completely assembled heater. A

Fig. 2 illustrates one of the insulator channels used to space the heating element from the plate.

Flgs. 3 and 4 illustrate two of the operations in assembling the heater. l

Fig. 15 is a bottom viewof a completely assembled heater with portions 'cut away 'to .which the heater coils 4 may be laid. One.

of the' insulator channels 5 .which are to space and insulate the coils'4 fromv thesurface plate 1 and its ribs 2. is clearly illus- 'trated in Fig. 2. It will be seen that this channel is adapted'to' enclose the coil on `three sides, and that the wall th'iclmess is very nearly uniform. This insures the coil being positioned in the grooves between the Iribs 2 so that the thermalpaths to the plate or its ribs-.are equal in all directions. This channel is preferably formed, of lavaI which 1 i is highly refractory and yet has a high'` conductivity as compared with insulating cements and the like. As shown in Fig.4 .2 the insulator channels are separately or previ-Av ously formed and bodily laid in the spaces betweenthe ribs, hence they may made with suiiicient accuracy to obtain a uniform thickness of the Walls. The heating element 4 used in this heater consists of helically wound coils of resistance Wire, and may be connected'in any convenient manner to a sourceof electricity throughbinding posts 6.

yThe heater plate may be conveniently assembled by inverting it, as invllig. 3, and

` placing the insulator lchannels 5 in the direct as much heat as possible to the surface plate. Inorder to insure a .rigid structure and preventbreakage of the insulating cement, a metal cover plate 9 is securely fastened to the flange 3 of the surface plate.

It is to be understood that this disclosure of a preferred embodiment is not to be c'onstrued asa limitation of this invention, as

' it-is'clear that the improved construction is applicable to many heating devices and may be considerably modified or adapted without departing.' from the spirit or scope of the invention.

' I claim:

1. An electric heater comprising a surface plate to be heated having metal ribs extending therefrom, lava channels disposed between said ribs, and a heatingelement disposed in said insulator channels, said channels serving to insulate said heating element from said plate and ribs.

2. A11 electric heater comprising a surface plate having ribs extending therefromv and integral therewith, `separately formed insulator channels of substantially constant wall thickness disposed between said ribs, and a lheating lelement disposed in said channels, said channels serving to position said wire equidistant from said plate surface andsaid adjacent ribs. Y

3. An electric heater comprising a sur-v -face plate having a continuous flange adjacent its perimeter and ribs extending therefrom to form grooves` separatelyformedinsulator channels of substantially constant wall`thickness disposed between said ribs, a heating element`l disposed in said channels, said channels and heating element being retained by -insulating material, anda cover plate attached to said flange to retain said insulating material, said channels serving to insulate said heating element from said surface plate and position saidv heating element equidistant from said plate and said adjacent ribs.

4. The combination with a heater plate having ribs extending therefrom to form troughs, of a heating elementI positioned between sa-id ribs and lava channels partially surrounding said coils. said channels serving toinsulate said coils from said ribs and plate and to position said coils from said ribs a distance substantially equal to the distance from 'said surface plate to lsaid heating element.

5. An electric heater comprising a. surface plate having ribs extending therefrom and integral therewith, separately formed insulator channels of substantially constant wall thickness disposed between said ribs, a heating element disposed in said channels, said channels serving to position said wire equidistant'from said plate surface and said .adjacent ribs, insulating cement covering said coils and 'said channels, and a cover plate attached to said surface plate to retain said insulating cement. t

6. An electric lfeater comprising a surface plate nhaving metal ribs extending therefrom, a heating element disposed between said ribs, lava channels surrounding said coils on three sides, and cement covering `the coils on the remaining side, said ANsoN s. mon. Louis J. FULLER.

rcement serving to retain said coils and 

